A versatile British character actor, Broadbent began his career on the London stage, performing with the Royal National Theatre and the Royal Shakespeare Company. He has frequently collaborated with writer and director Mike Leigh. They first worked together in Leigh's play Ecstasy (1979), following with Goosepimples (1981). Life Is Sweet (1991) marked their first film project. Broadbent won wide praise for his role as opera composer W.S. Gilbert in Leigh's acclaimed Topsy-Turvy (1999).

He made his film debut in 1978's The Shout and appeared in Terry Gilliam's Time Bandits (1981) and Brazil (1984). Broadbent's plate was full in 2001, appearing in Bridget Jones's Diary,Iris, and Moulin Rouge. He won a Golden Globe and a Best Supporting Actor Oscar for his performance as Iris Murdoch's husband in Iris. His other films include The Crying Game (1992), Enchanted April (1992), and Little Voice (1998).